I have done this a couple of times. I think I copied the coordinates of the electrodes from the .pom file to a plain txt file, with the channel numbers preceding the coordinates. Then copy and paste the NAS, RPA and LPA coordinates before the electrode coordinates.
Or also, I think what you can do is just import the CURRY functional data file right into brainstorm, in that file are the coordinates and ECOG data together. That is much easier.
I’m not at my CURRY workstation right now so I can’t confirm what I say, I may not be 100% correct.